Laser process yields tougher dies for auto manufacturing

Industrial PhotonicsJan 2014
Making dies using deep drawing puts them under immense pressure, but using a laser to alloy their surfaces with filler material makes them more robust and resistant to wear – increasing their service lifetime in automotive manufacturing by 150 percent.

To function properly, the dies must be maintained regularly and, in extreme cases, replaced; this can mean expensive manufacturing equipment stands idle for up to an hour. Moreover, pressed dies are costly, one-of-a-kind items made from special raw materials. Even dies just a few centimeters in size can cost up to €600 (about $821).

What manufacturers need are processes that increase the lifetime of dies and reduce setup times. One such method is laser metal deposition, in which a laser beam carefully melts the surface of the die and the filler material to produce a local layer that guards against wear on the die surface. This increases the robustness and resilience of the stainless steel die at critical points, all in a fraction of a second. What has been lacking until now, however, is a universal, reproducible process for practical industrial use.

The researchers rebuilt a conventional five-axis milling machine so that it could be used to alloy forming dies automatically via a laser. The machine can be embedded into the current manufacturing process and increases the lifetime of dies by more than 150 percent.

The new process also improves the quality of components and makes it possible to plan setup times with greater precision, as practical tests carried out on Mühlhoff’s premises have shown. Mühlhoff, based in western Germany, manufactures sheet metal components for the automotive industry. The company’s own tool shop supplies its various production locations with forming dies.

Another key part of this system is the integrated CAx (computer-aided) software, which allows all the requisite laser surface treatment processes to be controlled in a clear, reproducible manner. All necessary process parameters are transmitted to the machine without needing any interface. Processes can be simulated in detail and optimized in advance of actual processing operations.

In 2010, more than 60 partners from industry and research joined together in InnoCaT with the aim of carrying out joint research into innovations and synergies along the automotive process chain. For the first time, they analyzed the complex production flows in their entirety and from a resource efficiency perspective, taking in each stage from toolmaking to pressing, car body construction, and painting car body shells. Five collaborative projects and 30 subprojects yielded technical solutions and general approaches for increasing energy and resource efficiency before the initiative came to an end this past summer.

The researchers planned to demonstrate the work at the EuroMold trade show in Frankfurt in December.